This thesis is directed towards the development of the diffusive gradients in thin films (DGT) technique for the measurement of total dissolved As, and for As speciation measurements. In addition, a preliminary investigation of a novel laboratory-based method for measuring labile metal species was carried out; this method involved the coupling of a microcolumn of adsorbent with a standard electrothermal atomic absorption spectrometer. An iron-oxide adsorbent was utilized for As measurements by DGT. The diffusion coefficients of inorganic Asv and AsIII> were measured through the polyacrylamide diffusive gel using both a diffusion cell and DGT devices. A variety of factors that may affect the measurement of total As by DGT were investigated. These factors, which included pH, anions, cations, fulvic acid, FeIII-fulvic acid complexes, and colloidal Fe, may affect the adsorption of the As species to the iron-oxide, or may affect the diffusion coefficients of the individual As species. The DGT method was further developed to selectively accumulate the AsIII species in the presence of Asv. This was achieved by the placement of a negatively charged Nafion membrane at the front of the DGT device which slowed the diffusion of the negatively charged Asv species (H₂AsO₄₂ ⁻) considerably, relative to the uncharged AsIII species (H₃AsO₃). The effect that pH, anions, and cations may have on the selective accumulation of AsIII, in the presence of Asv, was investigated. DGT devices without a Nafion membrane and with a Nafion membrane were deployed in natural waters to determine the total inorganic As and AsIII> concentrations, and to evaluate its performance. A preliminary investigation of the coupling of a microcolumn of Chelex-100 resin with a standard electrothermal atomic absorption spectrometer was undertaken to establish its value as a laboratory-based speciation method. This involved the examination of various microcolumn materials to accommodate the Chelex-100 resin, and finding an appropriate buffer that could be used to buffer the Chelex-100 resin without interfering with the ETAAS measurement. Furthermore, factors that may affect the uptake of metal by the Chelex-100 resin, such as concentration of buffer in solution, ionic strength, and conditioning of the Chelex-100 resin, were investigated.

Chitosan-based copolymers (CH-GL1:6, CH-GL1:1, CH-GL1:0.5, and CH-GL1:0.25) were prepared at variable weight ratios of chitosan (CH) to glutaraldehyde (GL). Physiochemical properties of cross-linked copolymers were characterized using FTIR (Fourier Transform Infrared) spectroscopy, PXRD (Powder X-ray Diffraction), CHN analysis, and thermogravimetric analysis (TGA). The swelling behaviour of the polymers along with chitosan was investigated. The sorption properties of copolymers with arsenate oxoanions were investigated at various pH using 10 mM phosphate buffer systems and also in aqueous solution without buffer. The Sips sorption model describes the best fit parameters for adsorption. The relative monolayer sorption capacities Qm (mg/g) of the adsorbents are given in parentheses in the following order: CH-GL1:1(14.4) > CH-GL1:0.5(12.0) > CH-GL1:0.25(10.3) > CH-GL1:6(2.24). In general, the sorption capacities are listed in descending order as follow: un-buffered > buffered (pH 5.0) > buffered (pH 8.5). The removal efficiencies for 20 mg of polymers over a variable concentration range ( 1-200 mg/L) of arsenate in aqueous solution without buffer are as follow: CH-GL-1:1(20-95%), CH-GL1:0.5(14-97%), CH-GL1:0.25(10-98%), CH-GL1:6(2.0-56%), and CH (0.007-3.9%). The sorption properties of the adsorbents were also determined in bicarbonate buffer to evaluate the competitive effect of phosphate buffer on adsorption of arsenate oxoanions. X-ray absorption spectroscopy (XAS) of chitosan and CH-GL1:1 was performed after adsorption at different pH conditions using two buffer systems to evaluate the chemical environment around the arsenate species. In addition, sorptive properties of phenolic adsorbate (i.e. PNP) were estimated with CH-GL copolymers at various pH conditions. The estimated sorptive capacities (Qm; mmol/g) for PNP are in the range 0.07-0.21(mmol/g) while removal efficiencies for PNP are greater at lower pH conditions.

This thesis is directed towards the development of the diffusive gradients in thin films (DGT) technique for the measurement of total dissolved As, and for As speciation measurements. In addition, a preliminary investigation of a novel laboratory-based method for measuring labile metal species was carried out; this method involved the coupling of a microcolumn of adsorbent with a standard electrothermal atomic absorption spectrometer. An iron-oxide adsorbent was utilized for As measurements by DGT. The diffusion coefficients of inorganic Asv and AsIII> were measured through the polyacrylamide diffusive gel using both a diffusion cell and DGT devices. A variety of factors that may affect the measurement of total As by DGT were investigated. These factors, which included pH, anions, cations, fulvic acid, FeIII-fulvic acid complexes, and colloidal Fe, may affect the adsorption of the As species to the iron-oxide, or may affect the diffusion coefficients of the individual As species. The DGT method was further developed to selectively accumulate the AsIII species in the presence of Asv. This was achieved by the placement of a negatively charged Nafion membrane at the front of the DGT device which slowed the diffusion of the negatively charged Asv species (H₂AsO₄₂ ⁻) considerably, relative to the uncharged AsIII species (H₃AsO₃). The effect that pH, anions, and cations may have on the selective accumulation of AsIII, in the presence of Asv, was investigated. DGT devices without a Nafion membrane and with a Nafion membrane were deployed in natural waters to determine the total inorganic As and AsIII> concentrations, and to evaluate its performance. A preliminary investigation of the coupling of a microcolumn of Chelex-100 resin with a standard electrothermal atomic absorption spectrometer was undertaken to establish its value as a laboratory-based speciation method. This involved the examination of various microcolumn materials to accommodate the Chelex-100 resin, and finding an appropriate buffer that could be used to buffer the Chelex-100 resin without interfering with the ETAAS measurement. Furthermore, factors that may affect the uptake of metal by the Chelex-100 resin, such as concentration of buffer in solution, ionic strength, and conditioning of the Chelex-100 resin, were investigated.

Thesis (M.Eng.). / Written for the Dept. of Mining and Materials Engineering. Title from title page of PDF (viewed 2009/06/17). Includes bibliographical references.

No description available.

Thesis (PhD)--Montana State University--Bozeman, 2008. / Typescript. Chairperson, Graduate Committee: Timothy R. McDermott. Includes bibliographical references.

In 1977, sixty-two white spruce pole sections were installed at the Western Forest Products Laboratory's Westham Island test field site. They had been commercially pressure-impregnated with ammoniacal copper arsenate (ACA) or pentachlorophenol (PCP). Twenty-four of the ACA-treated spruce poles were studied to determine the influence of preservative penetration, retention, and nitrogen level on decay resistance of spruce poles after seven years of field testing. Such information was considered of great value in establishing treated spruce as viable pole material in Canada. Studies using a 0.5% solution of chrome azurol S indicated that for the ACA-treated spruce poles after seven years in test, average preservative penetration of 1.14 in. (2.90 cm) was generally greater than that required by Canadian standards. However, analysis using energy-dispersive X-ray spectrometry showed that the mean retention of 0.50 lb./ft.³ (8.06 kg/m³) was less than the level of 0.6 lb./ft.³ (9.6 kg/m³) for ACA, required by the CSA standard. It was also found that copper was present in greater quantity than arsenic, in spite of their equal presence in the original ACA treating solution. In microbiological studies, a total of seventy-one fungal isolates belonging to seventeen genera and four taxa were identified to genus, with fifteen of these identified as to species. Unlike the untreated control poles, true wood-decaying Basidiomycetes were not found associated with the ACA-treated spruce poles. Analysis employing an Orion ammonia-specific electrode coupled to an Orion Microprocessor ionalyser 901 revealed that nitrogen content due to ACA treatment was significantly increased in the treated zone and also beyond the penetration limit of preservative. A linear relationship existed between nitrogen content and chemical retention in the first analytical zone. Variation in moisture content above the fiber saturation point produced marked changes in electrical resistance as detected by Shigometer measurements. The practical application of the Shigometer for detection of internal decay is limited by such inconsistencies. / Forestry, Faculty of / Graduate

Increasing volumes of Chromated Copper Arsenate (CCA) treated wood materials are being removed from service, either as a result of reaching the end of their service life or being replaced with non-treated wood materials. These materials, while not regulated as hazardous wastes, have the potential to leach toxic metals into the environment. Incineration and landfilling are not ideal disposal methods as incineration could result in the volatilization of carcinogenic arsenic and chromium, while landfilling requires the waste to be sorted and placed in appropriately lined landfills to prevent contaminant release. Viable disposal methods must be considered to manage the significant waste stream of CCA-treated wood. This study investigates pyrolysis and electrokinetics (EK) as possible remediation techniques for the treatment of CCA-treated wood waste. A unique bench pyrolysis reactor was designed and optimized over three pyrolysis temperatures for retention of CCA metals within the char and bio-oil pyrolysis products. A batch pyrolysis system was constructed to produce large quantities of pyrolysis char for use in EK experiments. Mass balances were performed across both bench and batch pyrolysis systems, with metal distribution trends ascertained. EK experiments were performed on the char generated during batch pyrolysis as well as CCA-treated wood waste to evaluate the efficiency of coupling the two technologies. These EK studies were performed using pH regulation at the cathode and applying constant current. Distribution of the CCA metals post-EK experiment was determined and removal efficiencies were calculated. The mobility of the CCA metals was evaluated during all phases of this investigation using Toxicity Characteristic Leaching Procedure (TCLP), Synthetic Precipitation Leaching Procedure (SPLP), and Deionized Water Leaches to determine the likelihood of metal leaching under different environmental conditions.

The focus of this research is to determine the effects of particle size reduction and chemical pretreatment with strong base oxidizers on the effectiveness of the electrokinetic remediation of wood waste contaminated with chromated copper arsenate. Selection of an oxidative chemical pretreatment solution involved an initial screening between three pre-selected chemicals followed by optimization of oxidative chemical solution strengths and solid to liquid ratios. Samples of each of the three particle sizes were chemically treated with the final oxidative pretreatment and loaded into electrokinetic units where a direct current was applied for approximately fifty days. Similar experiments were performed without subjecting the contaminated wood to oxidative pretreatment to serve as an experimental control. It was identified that oxidative pretreatment of the lowest particle size prior to electrokinetic treatment was able to remove the highest percentages of chromium (75 %), copper (95 %), and arsenic (92 %) from the contaminated wood.

No description available.